Many medicaments are most effective when administered continuously over an extended period of time. While it has been possible to administer some of these medicaments by way of an intravenous drip or by the serial administration of the medicament either orally or hypodermically, the requisite monitoring of an intravenous drip restricts this modality to a hospital or other care intensive facility and oral or hypodermic serial administration requires either repeated visits to a healthcare provider or a strict adherence to the regimen by the patient. Examples of strict regimen therapies include those for fertility control and tuberculosis treatment. However, since many of the patients under such treatment do not have adequate access to healthcare providers, it is desirable to have a treatment modality which will minimize the number of visits to a healthcare provider while not requiring active participation on the part of the patient. To meet these goals, research in the last few years has been directed toward creating implantable sustained release implants or particles which contain the desired medicaments.
These sustained release implants or particles take on many forms. Some implants or particles are made of bioerodible polymers which release entrapped medicaments as the polymer is degraded within the body. In these devices, the rate of matrix erosion determines the rate at which the medicament is released. Other implants or particles consisting of a high porosity matrix rely on the time it takes a medicament located within the pores of the matrix to diffuse from the particle or implant.
Although sustained release implants or particles are being used in a number of different therapeutic regimens, a concern has recently arisen regarding the standard methods by which the particles or implants are fabricated. Typically polymers which form the implant or particle are dissolved in a solvent during the formation of the implant. Trace quantities of solvent may remain in the polymer during implant fabrication and patients receiving these implants or particles are exposed to the dangerous solvents which are released as the implant erodes.
The present invention relates to a solvent free method of producing bioerodible implants and particles for the administration of medicaments which permits the rate of release of the medicament to be controlled.